Adding disconnected as the preferred term

Author: bergerhoffer

contributing_to_docs/term_glossary.adoc

@@ -214,6 +214,15 @@ instance / cluster as an "OpenShift deployment".
 
 Do not use: deployment configuration(s), deployment config(s)
 
+''''
+=== disconnected
+
+Usage: disconnected environment, disconnected installation
+
+Use "disconnected" when discussing installing a cluster in an environment that does not have an active connection to the internet. Use "disconnected" regardless of whether the restriction is physical or logical.
+
+"Disconnected" is the preferred term over "restricted", "air-gapped", or "offline".
+
 ''''
 === Dockerfile